Indirect addressing method and system for locating a target element in a communication network

ABSTRACT

A method of guaranteeing that a communication network server can reach an element that is remote from the network using a path or link which is automatically updated when the remote element is moved within the network. The method employs indirect addressing (lookup table), and is used, in particular, in network performance measuring systems.

The present invention relates to an indirect addressing method toguarantee the adequacy between a target element in a communicationnetwork and a link allowing the location of that target element by aserver connected to the network. It also relates to a systemimplementing this method. It has a particularly advantageous, though notexclusive, application in the field of modelling an information system,or communication network, for the purpose of measuring performance andservice quality monitoring within the information system.

The growing complexity of information systems which integrate, inparticular, client-server architectures and integrated local networks,is making it increasingly difficult to measure performance and toeffectively monitor service quality within these systems. Many systemsoffering solutions for managing such networks wish to improve thecontrol ergonomics of the systems by replacing the crude values,generally digital, intended to distinguish the entities connected to thenetworks, with a more explicit alphanumeric form. This is for examplethe case when the addresses or interface numbers of each entity in anetwork are replaced by a name directly indicating the entity inquestion such as, for example, “Ethernet”, “Serial”, etc. In practice,the name “Ethernet” is attached to a link that indicates the path to theentity in question.

Now, such a method can be a source of problems when the entity isphysically moved within the network without updating the link. Thus,when the user enters the name “Ethernet” in order to consult theassociated entity, he risks consulting an undesired entity or having anerror message.

The invention aims to overcome this drawback by proposing an indirectaddressing method or “Lookup Table”.

The objective of the present invention is to propose an indirectaddressing method making it possible to improve the ergonomics and themaintenance of a system for measuring the performance of a communicationnetwork.

Another objective of the invention is to obtain a considerable timesaving when it is a matter of finding, for example, the new location ofan entity that has just been moved.

These objectives are achieved with a method for locating a targetelement in a communication network by means of a link composed of afirst index and a descriptive name. The index can correspond to anaddress in the form of a number. The descriptive name can be inalphanumeric form in order to distinguish the target element easily.This name is defined in the server as a value that can be assigned to adescription variable, this description variable being defined by a setof description parameters. According to the invention, the methodcomprises a link updating process in which:

-   -   on the basis of the description name, the value of at least one        description parameter is determined by means of a description        table,    -   on the basis of the description parameter value thus determined,        a second index is determined by means of an indexing table, and    -   the link henceforth composed of this second index and of the        description name is updated.

The method according to the invention furthermore comprises aconsultation process in which:

-   -   on the basis of a reference value of the description parameter,        a new description name is determined by means of the description        table,    -   on the basis of a reference index, a new value of the        description parameter is determined by means of the indexing        table, and    -   it is checked if the new description name and the new value of        the description parameter thus determined respectively        correspond to a reference description name and to the reference        value of the description parameter; in the affirmative, the        target element is accessed via a reference link; in the        negative, the updating process is executed.

The reference can advantageously correspond to a preceding consultationprocess.

The index corresponds to an item of information on the physical locationof the target element. A modification of this location corresponds to amodification in one of the tables. The invention is thus noteworthy bythe fact that it carries out an automatic updating of new locations.

According to the invention, the index can be defined in the server as avalue that can be assigned to an indexing variable, this indexingvariable being defined by a set of indexing parameters, this set beingat least a subset of the description parameters.

In other words, the method according to the invention uses two tables, afirst description table in which it is possible to determine the valueof the description parameters when a given description name is assignedto the description variable; a second indexing table in which it ispossible to determine a given index for given values of the descriptionparameters. These tables reflect the architecture of the network: if anelement of the network is moved or modified, at least one of the twotables is modified.

The consultation process corresponds to a normal functioning in whichthe server wishes to retrieve information relating to the targetelement. The server checks that the link conforms with the architectureof the network, that is to say that the description name correctlyrefers to the correct index. In order to do this, the precedingconsultation process is taken as reference, and it is checked that thedescription and indexing tables have not been modified. In the contrarycase, the updating process is carried out in order to find the new indexto which the description name describing the target element corresponds.

Advantageously, the index can correspond to an interface of a router towhich the target element is connected.

According to another aspect of the invention, an indirect addressingsystem is proposed for locating a target element connected to a routerof a communication network by means of a link composed of a first indexand a description name. The server comprises means for retrievinginformation relating to the target element on the router. According tothe invention, the server furthermore comprises, during an updatingprocess:

-   -   means for determining, on the basis of the description name and        within a description table, the value of at least one        description parameter,    -   means for determining, on the basis of the description parameter        value thus determined and within an indexing table, a second        index by means of an indexing table, and    -   means for updating the link henceforth composed of this second        index and of the description name.

Moreover, the server furthermore comprises, during a consultationprocess:

-   -   means for determining, on the basis of a reference value of the        description parameter, a new description name by means of the        description table,    -   means for determining, on the basis of a reference index, a new        value of the description parameter by means of the indexing        table, and    -   means for checking if the new description name and the new value        of the description parameter thus determined respectively        correspond to a reference description name and to the reference        value of the description parameter; in the affirmative, means        for accessing the target element via a reference link; in the        negative, means for executing the updating process.

Other features and advantages of the invention will furthermore appearin the following description. In the appended drawings, given asnon-limiting examples:

FIG. 1 is an overall block diagram illustrating a hardware architectureforming a communication network on which the method according to theinvention is implemented in the context of a system for measuring theperformance of the said network;

FIGS. 2, 3 and 5 each comprise a description table and an indexingtable, both of which illustrate a consultation process;

FIGS. 4 and 6 each comprise a description table and an indexing table,both of which illustrate an updating process.

A hardware architecture forming a network in which the method accordingto the invention is implemented will now be described with reference toFIG. 1. This network is composed of elements or entities (networkequipment, systems, etc) 1 to 7. The maintenance of the network iscarried out by the user 7 by means of performance measuring softwareinstalled in the server 6. A user can also act directly on the server 6when provided with the necessary display and data entry means (screenand keyboard). The router 1 comprises a plurality of interfaces I1, I2,. . . , to which are connected the entities 2, 3, 4 and 5, referred toin an overall manner by the expression “remote resources”. Each resourcecan be referenced by an index corresponding to an interface number towhich it is connected: the index “1” corresponding to the interfacenumber I1, for example. Furthermore, each resource has an explicitdescription name, or example such as “ETHERNET” for the resource 2, or“SERIAL 1” for the resource 3. An index attached to a description nameconstitutes a link that the server 6 records during the installation ofthe network.

The functioning of the maintenance software is such that when the userwishes to obtain information on the resource 2, he entered thedescription name “ETHERNET” and the server 6 establishes a formula suchas, for example in the case of simple indirect addressing:IfInOctets[ifDescr=“Ethernet”] IfInOctets[ifIndex=3]

This amounts to counting the number of bytes entering through theinterface I3 (index equal to 3), in other words, the link “3 ETHERNET”is activated. However, when the resource 2 is moved, it is necessary toupdate the new location of that resource.

The principal processes allowing this automatic updating will now bedescribed with reference to FIGS. 2 to 6 successively and using themaintenance software in a multiple addressing configuration.Furthermore, this software processes data coming from any equipmentsupporting the SNMP (Simple Network Management Protocol) protocol andincludes a dedicated support for the Remote Monitoring (RMON) MIBstandard. This standard support allows access to groups of variablessuch as nlMatrixDSTable or protocolDirTable.

It is considered, a priori, that the resource “ETHERNET” is connected tothe interface I3 and that the server wishes to execute the followingformula coming from the user 7:nlMatrixDSPkts[protocolDirDescr=*.ip.tcp.ftp]  (1)

where nlMatrixDSPkts is a variable of the nlMatrixDSTable group andprotocolDirDescr is a description variable of the protocolDirTablegroup. This description variable is defined by two descriptionparameters, protocolDirld and protocolDirParameters according to thetables TD and TL in FIGS. 2 to 6. Thus for each description nameassigned to the description variable protocolDirDescr, it is possible todetermine the values of the parameters protocolDirld andprotocolDirParameters.

In order to execute the formula (1), the server carries out an initialconsultation process illustrated in FIG. 2, that is to say averification in order to ensure that the link “3 ETHERNET” is effective.With the formula (1) and according to the RMON MIB standard, the serverexpects to find, in the place of the description variableprotocolDirDescr, a parameter called protocolDirLocalIndex which is infact the previously defined index. This parameter is not included in thenlMatrixDSTable group.

The server carries out a preliminary initialisation step in which itchecks that protocolDirLocalIndex is also found as an indexing variablein the protocolDirTable group of the description variableprotocolDirDescr. The indexing variable protocolDirLocalIndex is alsodefined by the parameters protocolDirld and protocolDirParameters. Theprocess then continues taking the tables TD1 and TL1 referenced in FIG.2.

In FIG. 2 the description variable protocolDirDescr can be assigned withthe description names of protocols such as *.ip.tcp.ftp-data,*.ip.tcp.ftp, ip.tcp.telnet, *.ip.tcp.smtp, *.ip.tcp.dns,*.ip.tcp.gopher, *.ip.tcp.www-http, *.ip.tcp.pop3, *.ip.tcp.nntp. Thereference data, in particular obtained after a preceding consultation,are such that ETHERNET corresponds to the values of the parameters(protocolDirld=64, protocolDirParameters=72). The consultation processin progress consists, starting from the pair (64, 72) and using thetable TD1, in verifying if the corresponding description name is stillETHERNET. In the table TD1, it is correctly found that (64, 72) givesETHERNET. Then, in the table TL1, it is seen that it is possible toassign location indices corresponding to the interfaces I1, I2, . . . tothe indexing variable protocolDirLocalIndex. Starting from the index“3”, it is checked that the values of the parameters are correctly (64,72). This first consultation process using the tables TD1 and TL1confirms that the link “3⇄ETHERNET” is effective. The formula (1) isthen modified by:nlMatrixDSPkts[protocolDirLocalIndex=3].

In FIG. 3, the server wishes to execute Formula (1) again but,meanwhile, the hardware architecture of the network has been modified byconnecting the resource 2 to the interface I7 of FIG. 1 and this hasresulted in a modification of the table TL according to FIG. 3. In orderto do this a second consultation process is started. A preliminaryinitialisation step is carried out and then the table TD2 is taken andit is verified that the pair of parameters (64, 72) corresponds to thedescription name “ETHERNET”. Then the table TL2 is taken and it is seenthat the index “3” does not give the pair (62, 72) but gives the pair(66,74). In this case, a process to update the link corresponding to thedescription name “ETHERNET” is initiated.

This updating process is illustrated in FIG. 4. The table TD3 is takenand, starting from the description name “ETHERNET”, the correspondingpair of parameters is determined. The pair (64, 72) is found. Table TL3is then taken and, starting from the pair (64, 72) thus determined inTD3, the corresponding index is determined and “7” is found. The servercan thus execute the formula (1) by replacing it with:nlMatrixDSPkts[protocolDirLocalIndex=7]

In FIG. 5, the server wishes to execute formula (1) again but,meanwhile, the hardware architecture of the network has been modified.The resource 2 is henceforth accessible via the interface I1 such thatonly the table TD4 has been modified. A third consultation process isstarted. A preliminary initialisation stage is carried out and thentable TD4 is taken and, starting from the pair of parameters (64, 72) acheck is carried out to see if the corresponding description name isactually “ETHERNET”. It is found that the pair (64, 72) corresponds tothe description name “SERIAL0”. In this case, an updating process isinitiated, The pair of parameters corresponding to the index 7 can alsobe determined from the table TL4. (64, 72) is found and therefore therehas been no modification in that table TL5.

FIG. 6 shows the second updating process which makes it possible todetermine, by means of the table TD5, that the pair of parameters (17,70) corresponds to the description name “ETHERNET” and that, by means oftable TL5, this pair of parameters (17, 70) corresponds to the index 1,that it to say to the interface I1. The server can thus execute theformula (1) by replacing it with:nlMatrixDSPkts[protocolDirLocalIndex=1].

The invention is not of course limited to the examples that have justbeen described and numerous modifications can be applied to theseexamples without departing from the scope of the invention.

1. Indirect addressing method, comprising the step of: locating a remoteresource reference to a router, in a communication network, with aserver of the network using a link composed of a first index and adescription name to allow a performance measuring software to locatesaid remote resource from the description name, in said locating step,the server carrying out an updating process in which: on the basis ofsaid description name, the value of at least one description parameteris determined by means of a description table contained in the router,on the basis of the description parameter value thus determined, asecond index is determined by means of an indexing table, and the linkhenceforth composed of this second index and of the description name isupdated in the server.
 2. Method according to claim 1, furthercomprising a consultation process in which: on the basis of a referencevalue of the description parameter, a new description name is determinedby means of the description table, on the basis of a reference index, anew value of the description parameter is determined by means of theindexing table, and checking if the new description name and the newvalue of the description parameter thus determined respectivelycorrespond to a reference description name and to said reference valueof the description parameter; in the affirmative, the remote resource isaccessed via a reference link; in the negative, the updating process isexecuted.
 3. Method according to claim 2, wherein said description nameis defined in the server as a value that can be assigned to adescription variable, said description variable being defined by atleast said description parameter.
 4. Method according to claim 1,wherein said description name is defined in the server as a value thatcan be assigned to a description variable, said description variablebeing defined by at least said description parameter.
 5. Methodaccording to claim 1, wherein said index is defined in the server as avalue that can be assigned to an indexing variable, said indexingvariable being defined by a set of indexing parameters, this set beingat least a subset of the description parameters.
 6. Method according toclaim 1, wherein said index corresponds to an interface of a router towhich said remote resource is connected.
 7. Method according to claim 1,wherein the reference value of the description parameter, the referencedescription name, the reference index and the reference link correspondto the data used during a preceding consultation.
 8. Indirect addressingsystem for locating a remote resource connected to a router of acommunication network, wherein a server of the network uses a linkcomposed of a first index and a description name to allow a performancemeasuring software to locate said remote resource from the descriptionname, the server comprising means for retrieving information relating tosaid remote resource on the router, wherein the server furthermorecomprises, during an updating process: means for determining, on thebasis of the description name and within a description table, the valueof at least one description parameter, means for determining, on thebasis of the description parameter value thus determined and within anindexing table, a second index by means of the indexing table, and meansfor updating said link henceforth composed of this second index and ofsaid description name.
 9. System according to claim 8, wherein theserver furthermore comprises, during a consultation process: means fordetermining, on the basis of a reference value of said descriptionparameter, a new description name by means of the description table,means for determining, on the basis of a reference index, a new value ofthe description parameter by means of the indexing table, and means forchecking if the new description name and the new value of thedescription parameter thus determined respectively correspond to areference description name and to said reference value of thedescription parameter; in the affirmative, means for accessing the saidremote resource via a reference link; in the negative, means forexecuting the updating process.